Commonize Char.titlecaseChar() and Char.titlecase() #KT-44369

libraries/stdlib/js/src/generated/_TitlecaseMappings.kt

@@ -0,0 +1,26 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.text
+
+//
+// NOTE: THIS FILE IS AUTO-GENERATED by the GenerateUnicodeData.kt
+// See: https://github.com/JetBrains/kotlin/tree/master/libraries/stdlib
+//
+
+// 4 ranges totally
+@OptIn(ExperimentalStdlibApi::class)
+internal fun Char.titlecaseCharImpl(): Char {
+    val code = this.toInt()
+    // Letters repeating <Lu, Lt, Ll> sequence and code of the Lt is a multiple of 3, e.g. <DŽ, Dž, dž>
+    if (code in 0x01c4..0x01cc || code in 0x01f1..0x01f3) {
+        return (3 * ((code + 1) / 3)).toChar()
+    }
+    // Lower case letters whose title case mapping equivalent is equal to the original letter
+    if (code in 0x10d0..0x10fa || code in 0x10fd..0x10ff) {
+        return this
+    }
+    return uppercaseChar()
+}